As part of irradiation studies performed in a fast-neutron nuclear reactor (FNR), sintered calcium hydride is used, and acts as a moderator of the nuclear fission reaction.
This material is present generally in the form of wafer cores which are stacked in an impervious cylindrical cladding made of steel.
When the irradiation studies have been performed, a cladding is obtained within which there are wafer cores presenting both a radiological risk (presence of radioactive substance such as a substance containing tritium) and also a chemical risk, since, on contact with water, calcium hydride gives off hydrogen, which is an extremely flammable gas.
The processing stream for the treatment of nuclear wastes requires the chemical risk to be neutralized while the volume of the wastes is reduced as far as possible, and their subsequent conditioning is optimized.
In order to respond to this twofold requirement, therefore, it would be desirable to have a treatment at the end of which, on the one hand, the wastes stemming from the cladding, and, on the other hand, the wastes stemming from the irradiated calcium hydride wafer cores, are removed by processing streams appropriate to the nature of each waste.
In practice, this requires that any pollution, particularly radioactive pollution, of one waste by another should as far as possible be limited.
If such a result is achieved, this has the advantageous effect of allowing:                the cladding to be removed to a processing stream in which waste management is simplified by the absence of radioactive substance, or even allows this cladding to be recycled (transformation or re-use);        management of the waste stemming from the irradiated calcium hydride wafer cores, in the form of a waste product suitable for the processing streams for removal of radioactive wastes.        